In an amazing discovery in Nanoscience, scientists at Tufts University have made the world's smallest electric motor from a single molecule and the discovery may well find its place in the Guinness World Records.
The latest electric motor, which could be used in various applications ranging from medicine to engineering, measures a mere 1 nanometer across, a groundbreaking work considering that the current world record is a 200 nanometer motor. As a result, the new microscopic motor could replace it as the tiny motor is just one nanometer across, about 60,000 times smaller than the width of a human hair.
Single-molecule motors are not new, and previous research groups had shown an ability to get individual molecules to respond to stimulus from light or from chemicals. But this is the first time that electrically-driven molecular motors have been demonstrated despite a few theoretical proposals and it has significant advantages over those other technologies.
There has been significant progress in the construction of molecular motors powered by light and by chemical reactions, but this is the first time that electrically-driven molecular motors have been demonstrated, despite a few theoretical proposals, said Charles Sykes, associate professor of chemistry at Tufts. We have been able to show that you can provide electricity to a single molecule and get it to do something that is not just random.
Sykes and his colleagues were able to control a molecular motor with electricity by using a state of the art, low-temperature scanning tunneling microscope (LT-STM), one of about only 100 in the United States. The LT-STM uses electrons instead of light to see molecules.
Researchers have used the metal tip on the microscope to provide an electrical charge to a butyl methyl sulfide molecule that had been placed on a conductive copper surface. This sulfur-containing molecule had carbon and hydrogen atoms radiating off to form what looked like two arms, with four carbons on one side and one on the other. These carbon chains were free to rotate around the sulphur-copper bond at speeds of up to 120 revolutions per second.
Scientists found that a freezing minus 268 degrees centigrade proved ideal for tracking the motor's motion as direction and speed were affected by temperature. At this temperature, the researchers were able to track all of the rotations of the motor and analyze the data.
The team determined that by controlling the temperature of the molecule they could directly impact the rotation of the molecule. Researchers said the practical applications of the electric motors would increase when the optimum operational temperature is determined. The motor spins much faster at higher temperatures, making it difficult to measure and control the rotation of the motor.
Once we have a better grasp on the temperatures necessary to make these motors function, there could be real-world application in some sensing and medical devices which involve tiny pipes, said Sykes.
Meanwhile, coupling molecular motion with electrical signals could also create miniature gears in nanoscale electrical circuits. These gears could be used in miniature delay lines, which are used in devices like cell phones.
By slightly modifying the molecule, the molecular electric motors could be used to generate microwave radiation or to couple into nano-electromechanical systems (NEMS).
The next thing to do is to get the thing to do work that we can measure - to couple it to other molecules, lining them up next to one another so they're like miniature cog-wheels, and then watch the rotation propagation down the chain, said Sykes.
The research team, which plans to submit the Tufts-built electric motor to Guinness World Records, has published a paper detailing the new electric motor in Nature Nanotechnology on Sept.4.
Watch the below video explaning the making of tiny electric motor: